Method of manufacturing sand molds for metal castings



April 18, 1939. E F. OYSTER ET AL 2,55,099

METHOD OF MANUFACTURING SAND MOLDS FOR METAL CASTINGS Filed Jan. 19, 1938 3 Sheets-Sheet l vApril 18, 1939-. E. F. oYsTER Er Al. 2,155,099

METHOD OF MANUFACTURING SAND MOLDS FOR METAL CASTINGS Filed Jan. 19, 1958 s sheet's-sheet 2 m mmmnmntors Y (ttorneg April l18, 1939. E, F, @v51-ER Er AL 2,155,099

METHOD OF MANUFACTURING SAND MOLDS FOR METAL CASTINGS Filed Jan. 19, 1938 sheets-sheet 3 Znvenfors (Ittomeg vPatented Apr. 1s, 1939 METHOD PATENT OFFICE F MANUFACTURING SAND 'MOLDS FOR LIETAL CASTINGS Earl F. Oyster, Shaker Heights. and Frank T.

i Spikerman, Clinton, Ohio l AppllcationJanuary 19, 1938, Serial No. 185,702

. 3 Claims;

This invention relates to improvements in the art of manufacturing sand molds for metal castings.

While the invention is intended for use generally wherever it may be advantageously employed, it is particularly adapted for use in forming sand molds for casting brake shoes.

In making sand molds for brake shoe castings, it is necessary to use chills which are placed on the pattern and which project beyond the sides thereof thus creating a back draft, or cavity which must be completely packed with sand to produce a usable mold. The ramming'or packing of the molding sand in making brake shoe molds must be accomplished without disturbing the position of the chills and the molding sand must be firmly packed under the projecting edges of the chills which are placed on the pattern prior to the act of ramming the mold.

In the manufacture of sand molds, it is necessary to pack the sand solidly about the pattern. This has been done by tamping in which a downward pressurel is applied to the surface of the sand; by jolting, in a series of impact blows transmitted to the sand causing the same to settle and pack to the required density; by peaning, in which pressure is applied to a pean which is forced downwardly into the sand in the deep portions of the mold and by squeezing, in which a squeeze head is brought into forced contact with the surface of the sand. While all of these operations have been employed in mechanical molding methods and accomplished on molding machines it has been found impossible to impart sufficient lateral flow to the sand to pack it under the edges of chills and other projecting ledges. In tamping, jolting, peaning or squeezing, the movement of the sand is downwardly with no beneflciallateral packing action as the sand arches under the pressing member, thereby limiting the horizontal movement thereof. Heretofore it has been necessary to resort to tucking to accomplish this result. Tucking a mold of this character has never been successfully accomplished by mechanical methods and it has been necessary to perform this operation by hand labor.

It is a purpose of this invention to provide a method by which mechanical means can be employed to destroy the arching action of thessand and force it downwardly, laterally and upwardly and solidly pack the same under the projecting ledges of a pattern, under chills, ram-up cores and other projecting parts of a pattern whereby perfect molds of the character indicated can be produced on a molding machine.

It is an objectfof this invention to provide'au v improved method of manufacturing such molds in which a molding machine may be employed-- to quickly and accurately produce molds of the character above indicated and in which the sand 5 is firmly and uniformly packed.

Other objects are to provide amethod of man- Y ufacturing molds which will include, simultaneously subjecting the sand to a peanlng squeeze and to oscillatory impacts or vibrations and to 10 subject the s and to a squeeze pressure and to lm pacts and vibrations to break the resisting arch Y in the sand and give it a settling movement inboth a vertical and a horizontal direction.

The above objects are accomplished and l5 tional ends are attained bythe novel method herein described with reference to the accompanying drawings in which there 'is illustrated practical means for carrying the invention into. Y eiect, it being understood that changes and 20 modifications may be made which come within 'a the scope of the claims hereunto appended.'

In the drawings: y Figure 1 is a front, elevational view of the molding machine herein described with 'parts' shown 64 in vertical section to more clearly illustrate thel invention, Figure' 2 is a side elevational view of same, Figure 3 isa horizontal, sectional view taken' as l indicated by the lines 3-3`of Figure 1,

oscillating cylinder employed in reducing the ln#- vention to practice, Y

Figure 5 is a. vertical, sectional lview of a pat-h -I tern plate showing the stripping plate and flask Slin with the pattern operatively positioned therein,-

the same being shown with portions of the pearl- In the drawings there is shown a molding man chine having a conventional base 6 providing a g vertical, hollow. cylinder in which there is operatively mounted a piston provided at the upper 48 end thereof with a tablel. The table l is provided on the upper face thereof with a plurality.` of hollow bosses 8 each of which is arranged ad-l 'y jacent a corner thereof and in which is slidably received the lower ends of the pins 9. 156 The numeral I 0 denotes an oscillator table" which is provided with a plurality of bosses Il which project from the downwardly presented side of the table, each in axial alinement with `one ofthe bosses 8. Each ofthe pins Care 30; Figure 4 is a. longitudinal, sectional view of the-- secured in one oi' the bosses II and a. coil spring 3a is mounted von each pin to normally bear the vweight of the oscillator table Ill. The oscillator table Ill is also provided on the lower side thereof with a centrally positioned, downwardly projecting web I2 on which is mounted an oscillator cylinder I3. The cylinder I3 is bolted or otherwise securely attached to the Web with its axis disposed at approximately a 45 angle to a horizontal plane. Each end of the cylinder I3 is securely closed by means "f the heavy plugs I4 and a hammer in the form of a piston I5 is mounted for reclprocatory motion in the cylinder.

'I'he piston I5 is provided with two circumferentially extending channels I6 whi'ch are arranged in spaced relation around the middle portion of the piston to alternately communicate with the intake port I1. The cylinder I3 is provided adjacent each end thereof with exhaust ports I8 and a passage I9 in the piston I5 leads from each end of the cylinder to the' groove I6 positioned farthest therefrom. A suitable tube 20 may be connected to the cylinder I3 in communication 'with the intakev port I1 through which air or other fluid under pressure will cause a high frequency reciprocation of the piston I5 and will cause the ends thereof to be brought into forced contact with the oppositely positioned plugs I4 in very rapid succession, and cause a high frequency Vibration which is communicated to the spring supported oscillator table II).

The numeral 2l denotes a pattern plate which is positioned on the oscillator table I0 and which is provided Iwith suitable dowels 22. A stripping plate 23 is positioned on the pattern 2| and a flask is positioned in the usual manner on the stripping frame 23.

The dowels 22 project upwardly through suitable bores in the stripping frame and in the base flange of the flask to hold the flask in a proper position.

The numeral 28 denotes a pattern which is positioned on the pattern plate 2| and the numeral 24 denotes chills which are positioned on the pattern as`- shown in lthe drawings.` The vbase portion 6 is providedv with an extension 30 which projects rearwardly therefrom. A frame 3l projects upwardly from the extension 30 and a peaning arm 32 and squeeze arm 33 arehingedly secured thereto for swinging movement on vertical axes. The peaning arm 32 is provided with a suitable pean 21 which may be swung in position over the flask 26 as shown in the drawings.

In the drawings there is shown two patterns 28 positioned on the pattern plate 2l. A cross sectional view of the pean 21 is illustrated in Fignre 3 wherein there is shown side and end walls which are adapted to exert a pressure on the portion of the sand positioned between and surrounding the patterns.

In the particular adaptation of the invention shown, the pean has a middle wall 21a arranged to exert a pressure on the portion of the sand positioned between the patterns 28. The other arm 33 is. provided with a squeeze head 34 which may likewise be swung into a position above the one or both ends ofthe cylinder I3 results in a vibration or jarring movement of the spring supported table I0. As the cylinder I3 is positioned with its axis disposed at an angle to a hori-` zontal plane, the oscillation of the piston I6 in the cylinder I3 imparts a like impact or vibration to the sand 26 which settles the same both vertically and horizontally and completely and firmly packs the same in the space between the chills 24 whereby the sand subjected to the peaning squeeze ls true to the pattern. The pressure to the cylinder I3 is then discontinued and the table I0 is lowered, the pean is then swung to an inoperative position and the arm 33 is operated to bring the squeeze head 34 over the flask 26. Air or other fluid under pressure is then admitted to the cylinder 6 in the ordinary manner and the sand 25 is brought into forced contact with the squeeze head 34 to complete the packing of the sand 25 in the flask 26.

The draw cylinder 36 may be operated to raise the yokes 31 and push the draw pins 38 upwardly throughthe openings 39 in the table I0 and through coinciding openings in the pattern plate 2l to raise the flask and stripping plate upwardly and draw the same from the pattern 28.

`While we have shown and described an oscillating cylinder i3 having a piston l5 which impacts .against either end I4 of the cylinder i3, it is understood that the process includes a vibration or oscillation which may be caused by animpact against either end I4 of the ,cylinder I3 or any like movement produced by any suitable means. It will also be understood that the term oscillating impacts employed in the claims includes vibrations, oscillations or any like movement, and, while we have shown means for creating high frequency oscillations or vibrations, it will be understood that the impacts may be of any frequency which. will obtain the desired result.

By forcing the pean heads 21, 21a downwardly into the sand, pressure is applied directly to the deep portions thereof, but this operation alone is not sufcient to pack the sand ilrmly under the edges of the chills. subjecting the sand to oscillating impacts also settles and packs the same around the vertical and upwardly presented surfaces of the pattern but will not produce suihcient lateral movement of the sand to pack the same under the edges of the chills or other downwardly presented pattern surfaces. By simultaneously peaning the sand and subjecting it to oscillatory impacts as herein set forth, the arching action` of the sand is destroyed causing it to iiow downwardly, upwardly and horizontally packing it firmly beneath the projecting edge portions o f the chills 24 or other downwardly presented surfaces.

The invention thus provides an improved meth-v od which can be followed to mechanically produce sand molds for patterns having chills or other downwardly presented surfaces.

Having thus fully described our improved process, what we claim iszl. A method of making a 'mold comprising placing a lpattern in a flask, filling the flask with sand, piercing the sand on a relatively restricted area down to the region adjacent the pattern and simultaneously subjecting the sand to vibrations.

2. A method of making a mold comprising placing a pattern in a flask, filling the flask with sand, piercing the sand on a relatively restricted area to a level beneath the top of the pattern and simultaneously subjecting the sand to vibrations. the region of the pattern so as to cause the sand 3. A method of making a. mold around a patto ow under the shoulder on the pattern and tern having a shoulder beneath which sand must simultaneously subjecting the sand to vibrations. be placed. comprising positioning the pattern 5 within a ask. lling the ask with sand, piercing EARL F. OYSTER. 5

the sand on a relatively restricted area down to P i FRANK T. SPIKERMAN. 

